This invention is related to the field of nondestructive testing, and more particularly, to nondestructive testing utilizing ultrasonic waves.
The significant contributions which surface cracks make to the fracture of structural materials have recently become well recognized, with such cracks receiving more concentrated attention toward accurately and effectively predicting the failure of materials. A number of ultrasonic methods have been applied to the measurement of surface cracks in the past. Such prior art methods have utilized both bulk and surface wave methods, including pulse echo techniques, depth measurement from first principles, timing methods, and spectroscopic analysis. The known techniques, however, are subject to a number of shortcomings. Moreover, recent developments involving surface waves have provided new techniques for exciting high frequency waves and for generating such waves with increased efficiencies. Thus, a need has developed in the art for a surface wave flaw depth measurement method which may be related to the context of the fracture mechanics of part through cracks to delineate the stress intensity range and determine the remaining fatigue life for structural materials.